Belt grinder.

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John Hasler
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Re: Belt grinder.

Post by John Hasler » Fri Jun 29, 2018 10:08 pm

wlw-19958 wrote:
Fri Jun 29, 2018 8:48 pm
Hi There,
John Hasler wrote:
Fri Jun 29, 2018 8:32 pm
Do you use steel belts?
Are there steel abrasive belts? If so, where does one get them?

Good Luck!
-Blue Chips-
Webb
There are none that I know of but I would not be amazed to learn that they are used in some exotic corner of the aerospace or nuclear industries.

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SteveHGraham
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Re: Belt grinder.

Post by SteveHGraham » Fri Jun 29, 2018 10:14 pm

Instead of a flat platen, you can use a platen with a radius. It's like a platen which is a small segment of a very big circle. This should get rid of the problem Harold is talking about. Or you can grind up by the pulley, or you can use a contact wheel. People do hollow grinds with belts all the time.

I like belt grinders better than bench grinders for roughing. They're fast. If yours isn't fast enough, you can put a coarser belt on in 5 seconds. They also carry heat away from whatever you're grinding. Don't know how much it helps, because things do get hot.

Tubalcain the Youtube guy uses a 6x48 to grind drill bits. Not vouching for him. Just putting it out there. I would hope someone with his experience would know a sharp drill when he sees it, but maybe he doesn't.
Every hard-fried egg began life sunny-side up.

Harold_V
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Re: Belt grinder.

Post by Harold_V » Sat Jun 30, 2018 1:50 am

SteveHGraham wrote:
Fri Jun 29, 2018 10:14 pm
Tubalcain the Youtube guy uses a 6x48 to grind drill bits. Not vouching for him. Just putting it out there. I would hope someone with his experience would know a sharp drill when he sees it, but maybe he doesn't.
It isn't a matter of sharpness. It's a matter of decreasing relief as one approaches the cutting edge. Where it often shows is when you're taking fine cuts, where the relief may be down to zero. That's why I suggested looking at belt sanded surfaces with a critical eye---where the rounding is obvious.

I've used a belt for sharpening large drills on countless occasions. I simply provide greater relief, to ensure that the drill will cut (that helps offset the slight rounding that occurs). It bails you out, but it's no substitute for a properly ground drill. I'd be happier with a large drill pointer, but I don't have that luxury at my disposal.

H
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toglhot
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Re: Belt grinder.

Post by toglhot » Sat Jun 30, 2018 3:00 am

Relief is adjusted by adjusting the angle of the bit when sharpening. unfortunately, when using a round stone you may indeed finish with a more angled relief; however, that is offset by the heel of the relief jutting up so the extra relief angle is negated. If you find having a more acute relief is required, that can be accomplished, using a belt grinder. by simply adjusting the angle.

Incidentally if the belt were to bunch up the tool bit you are sharpening would tear the belt, its not rocket science! Belts are mean't to be taught for that very purpose - to stop the belt from bunching up and tearing. If you force the work onto the belt that much then you have no business using a belt or even a stone - common sense.

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Rich_Carlstedt
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Re: Belt grinder.

Post by Rich_Carlstedt » Sat Jun 30, 2018 9:04 am

Belts can work wonders
i have used belts for years for sharpening and they do a fantastic job.
The belt bunching up in front of the tool bit is true if you are a "hogger" or" clumsy" in technique
Those with some tool finesse however can achieve terrific results.
Angle of relief can be precisely controlled as the support plate on the belt machine is more easily set than on a pedestal grinder.
This is even easier if the tool bit is still in an Aloris tool holder for example.
Drawing magic marker lines on the plate helps get specific angles Too !- This works for threading tools like Acme threads where the average machinist is unaccustomed to those angles.
Belts are safer as well. They have low mass compared to grinding wheels and that means far less physical damage potential, especially for eyesight !
Now my favorite, I grind tools in every manner, including reverse or upside down.
Burrs are never a problem, because I always stone my work, but here is a helpful hint that only can be done on a belt machine.
When you have delicate work and donot want to over heat the steel (temper loss-which many newbies suffer !) use an ice cube against the toolbit. It keeps the work cool and any water that forms is directed below. Putting a ice cube on a grinding wheel, sends water spray all over the place and doesn't allow the same visionary view.

Rich
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Rich_Carlstedt
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Re: Belt grinder.

Post by Rich_Carlstedt » Sat Jun 30, 2018 9:19 am

Here is a Post-note on the design of some belt sanders.
It may be the reason that some have had failures in their efforts to use a belt machine
Pay attention to the "platen" on the belt machine.
This is the metal backing plate behind the belt that acts as a support when pushing against the belt.
On some machines, the platen is inline with the two wheels which are before and after the platen.
YOU DO NOT want such a machine !
This condition allows the belt to flap in operation. The Platen MUST stand proud of a direct line between the wheels.
Designers do not like much of that ( being proud) as it increases the HP requirement oof the machine.
However, the "proud" platen will smooth out the belt so it stays flat to the work piece.
Obviously if you run belts loose, they will flap as well, and there is a tendency for some to not run tight belts so they can get longer life.

Like anything, if you want to get good at what you do, Know thy machine !
Rich

John Hasler
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Re: Belt grinder.

Post by John Hasler » Sat Jun 30, 2018 9:56 am

Rich writes:
The Platen MUST stand proud of a direct line between the wheels.

As it does on both of my belt grinders (not that I'd use the big one for grinding cutters anyway). My small belt grinder also has a disk.

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SteveHGraham
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Re: Belt grinder.

Post by SteveHGraham » Sat Jun 30, 2018 11:27 am

Rich_Carlstedt wrote:
Sat Jun 30, 2018 9:04 am
The belt bunching up in front of the tool bit is true if you are a "hogger" or" clumsy" in technique
But enough about me.

One of the things I love about belt grinders is that you can lean in there and really hog out metal.
Every hard-fried egg began life sunny-side up.

toglhot
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Re: Belt grinder.

Post by toglhot » Sat Jun 30, 2018 8:05 pm

wlw-19958 wrote:
Fri Jun 29, 2018 8:48 pm
Hi There,
John Hasler wrote:
Fri Jun 29, 2018 8:32 pm
Do you use steel belts?
Are there steel abrasive belts? If so, where does one get them?

Good Luck!
-Blue Chips-
Webb
Zirconia belts are available for grinding metal; unfortunately, zirconia belts aren't available 25x760mm. Zirconia belts last a lot, lot longer. I have three belt grinders: A 6" wide slow speed for wood, a 4" wide zirconia belt machine for metal running at high speed and the one I made with a 1" wide belt. I also have two finger belt files: a B&D using 10mm wide belt and one I made myself from Delrin using 20mm wide belts and running off an 18 volt cordless battery. The 4" wide zirconia belts are excellent for removing loads of metal quickly but will burn wood if not careful, hence the 6" slow speed. I've found the 1" belt grinder superior to grind stones for sharpening, particularly for lathe cutting bits: using a course grit for shaping and the 1000 grit belts for a nice sharp edge. I can't use files anymore, hence the finger belt files.
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